<ol>
  <li>Preheat the oven to 400°F/200°C.</li>
  <li>Finely chop the red onions and sweat gently on a low heat in olive oil for 5 minutes.</li>
  <li>Peel the garlic and add it to the onions.</li>
  <li>Meanwhile, chop the bell peppers to 1 inch pieces. Add the bell peppers and tomatoes to a roasting dish, and rub with lemon juice, olive oil and black pepper. Transfer to the oven and roast for 30 minutes.</li>
  <li>Once the onions and garlic have softened, chop and add the chilies, seeds and all. Mix well and continue to gently fry.</li>
  <li>Thoroughly wash your hands following handling raw chilies.</li>
  <li>Once the tomatoes and bell peppers have finished roasting, add them to the pan. Cook for at least 10 minutes, breaking them up with a masher or a hand blender as they simmer. Once broken up, mix in the sugar.</li>
  <li>Transfer the sauce to a blender and blend until smooth.</li>
  <li>Return to the pan and add the vinegar and juice of the limes.</li>
  <li>Cook through for a further 10 minutes, then leave to cool.</li>
  <li>Transfer to sterilized jars and keep refrigerated.</li>
  <li>Leave for at least two weeks before tasting.</li>
</ol>
